1. Field of the Invention
The present invention relates to a novel powder having a particularly excellent sebum-adsorbent property, and to a cosmetics, sebum-adsorbent agent, a body deodorant and the like, each employing the novel powder. More particularly, it relates to a powder comprising a base substance usable as a powder for cosmetics, a hydroxyapatite and a zinc oxide, preferably to a powder obtained on coating the surface of the substance with hydroxyapatite and fixing zinc oxide to the hydroxyapatite coating layer thereof, and particularly suitable for use in cosmetics, such as a sebum-adsorbent agent, or a body deodorant, or the like. It is possible to provide cosmetics, a sebum-adsorbent agent, a body deodorant and the like by the use of the powder in the present invention.
2. Description of the Related Art
The sebum secreted from the skin affords an emollient effect to the stratum corneum of the skin which keratinizes normally, prevents intrusion of toxic substance or bacteria from the outside, and controls the release of substances, such as water, out of the body. However, excess secretion of the sebum has a demerit that it may be a factor or so causing the makeup to come off which leads to some phenomena, for example, a xe2x80x9cshinyxe2x80x9d or xe2x80x9cdrabxe2x80x9d appearance of the skin, or a xe2x80x9cunevennessxe2x80x9d, xe2x80x9crumplingxe2x80x9d, or xe2x80x9cdisappearancexe2x80x9d of the makeup itself, and the like caused by chronological changes in the cosmetic film that is coated on the skin, that may be due to the formation of peroxides by the oxygen contained in atmospheric air. Similar to photo-degradation of fats and oils, such formation of peroxides, if intruded into the skin, operates as irritants that may cause inflammation or a keratinization disorder, blemishes, or freckles on the skin. So, there is raised a demand for developing a technology for effectively removing sebum, wherein it takes account of safeness of the skin so as not to impose an excessive burden on the skin.
A variety of investigations have already been conducted from the viewpoint of improving long wear for makeup. For example, should highly moisture-absorbent or oil-absorbent substances, such as porous silica, calcium carbonate, magnesium carbonate, and crystalline cellulose, be mixed into cosmetics, moisture and sebum components on the skin become adsorbed, which leads to a shortage of skin emollient components and causes a dry skin feeling, and a tightness of skin or itchiness of skin. This phenomenon is most likely to occur with persons with dry skin and normal skin, in particular with persons living in an environment and the like (for example, persons working in an office) where perspiration (sweat) or sebum are not apt to be secreted. When used on oily skin, these substances have demerits, which are apt to present luster by the progress of the wet phenomenon due to excess sebum or oily components contained in the cosmetics, thus giving rise to a xe2x80x9cshinyxe2x80x9d look in the finished makeup.
Although cosmetics admixed with fluorine-processed powders have been proposed for improving the long wear for makeup, cosmetics making use of these powders, while not being wetted with sebum or perspiration, exhibits strong water- or oil-repellency thus causing the cosmetic film to be xe2x80x9crumpledxe2x80x9d due to slipping of the powder on the skin thus impairing the makeup effect.
The cosmetics employing the powders treated with silicone are high in water repellency and also exhibit resistance against perspiration and moisture. However, the silicone oil, and the silicone oil or its derivative which is applied for surface treatment of the powder are low in oil resistance, basically due to the basic structure which the silicone oil has. Consequently, in the case of a person with an oily skin, the makeup may come off from the entire face due to excess secretion of sebum. On the other hand, in the case of a person with normal skin, the makeup may come off at the T- or V-zone of the face, so that it is difficult to prevent the makeup from coming off due to secretion of sebum.
A film forming polymer material may be utilized for improving long wear for makeup. As representative of this type of substance, an acryl-silicone based graft polymer has been proposed. This is produced and obtained by radical polymerization of a dimethyl polysiloxane composite which has a radical polymerizability at one terminal end of the molecular chain with a radical polymerization monomer composed essentially of an acrylate or a methacrylate, and forms a cosmetic film superior in water- and oil-repellency so that it is made practicable in a non-aqueous foundation. However, the cosmetics employing these polymers, from the viewpoint of enveloping the skin, leave many problems of a physiological aspect in the skin when taking into consideration the everyday biological activity on the surface of the skin. Moreover, in powder products in which the skin-forming capability cannot be used effectively, long wear is difficult to be improved.
There are also proposed a zinc oxide coated substance in which a base substance is coated with an amorphous zinc oxide, and there are reported a powder exhibiting good spreadability without detracting from the fatty acid-solidifying capability and an external agent for skin, using this powder (see Japanese Patent Kokai Publication JP-A-9-227792). However, the amount of adsorption of an oleic acid, which the zinc oxide coated substance exhibits, is approximately the same as that of the normal porous silica and is not particularly excellent in adsorption of the free fatty acids. Moreover, the amount of adsorption of an artificial sebum, which this coated substance exhibits, is lesser than the porous silica beads, and furthermore this coated substance takes approximately 30 minutes to solidify fatty acids, thus presenting difficulties in coping with the oily skin or ultra-oily skin.
On the other hand, there are reports of a composite, which is inclusive of one or more oxides and/or their hydroxides in the inter-layer of the clay mineral or an inter-layer metal inclusive composite adsorbing selectively only free fatty acids (see Japanese Patent Kokai Publication JP-A-10-87420). This material uses a water-swollen type of clay mineral and is produced by the reaction in the sol-state. As may be understood from the description of the Examples thereof, the reaction takes place in the diluted solution. Therefore, this method is costly in production per batch and is economically unmeritorious. Moreover, since the reaction occurs in the sol-state, the washing process is extremely time-consuming, when a regular filtering, washing, and drying process is used. The process is not only extremely time-consuming, but also the obtained product aggregates strongly, thereby not obtaining the result that is expected. In addition, a freeze-drying process is essential so that production becomes very expensive as another weak point. Although AL pillars are formed in the inter-layer of the clay mineral, the variations of content of intercalated oxide or hydroxide generates different states of pillars because of differences between lots of the clay mineral, it is usually difficult to obtain products in the same stable quality.
There is also a demand for the development of a substance (agent) for absorbing, adsorbing, solidifying, or congealing the body odor (smell), which is a body deodorant, which may or may not be comprised in cosmetics.
Under these above circumstances, there is a demand to develop a suitable skin-friendly powder, wherein the powder improves long wear for makeup, and can improve the demerits of the above prior substances, and can adsorb sebum, and also has antibacterial effect and body deodorant effect, in particular keep a cleanness and safeness of the skin by the cosmetics, by removing the free fatty acid (in particular the unsaturated fatty acid) and the secreted sebum.
Problem to be Solved by Invention
In view of the above, it is a problem to be solved by the present invention to provide a material suitable for use in cosmetics and the like, wherein the material specifically adsorbs free fatty acids (in particular unsaturated fatty acids), and also adsorbs, solidifies or congeals the secreted sebum, does not obstruct the skin physiology by making a solid film form, and has a light reflection curve (reflected light curve) similar to that of the surface of skin, and has a good skin feeling and is superior in long wear effect for makeup and antibacterial effect, and also has a deodorant effect.
Means to Solve Problem
The present inventors have conducted perseverant researches towards solving the above problem, and found that a powder comprising a base substance usable as a powder for cosmetics, a hydroxyapatite and a zinc oxide, preferably a coated substance, obtained on coating a hydroxyapatite on the surface of the substance and fixing a zinc oxide, more preferably a low crystalline zinc oxide (and/or an amorphous zinc oxide) to the coating layer, in particular the surface of that, of the hydroxyapatite, has such superior effects. It has also been found that the powder is superior in sebum-adsorbent property (in particular, the powder has high adsorbent properties with respect to unsaturated fatty acid and sebum, and also the time for solidifying unsaturated fatty acid and sebum is short), and the powder has an antibacterial effect and a property for adsorbing body odor components. The above variety of knowledge has led to the completion of the present invention.
That is, the present invention resides in a powder comprising a base substance usable as a powder for cosmetics, a hydroxyapatite and a zinc oxide, preferably a powder comprising a base substance usable as a powder for cosmetics, a hydroxyapatite coated on the surface of said substance and a zinc oxide fixed to the coating layer of said hydroxyapatite. Preferably, that is a powder obtained on coating the surface of the substance with hydroxyapatite to form a hydroxyapatite coating layer on the surface of the base substance and fixing a zinc oxide to the hydroxyapatite coating layer thereof. Moreover, the powder is suitable as a powder for cosmetics so that the powder can be applied to the cosmetics admixed with the powder, or to other fields of use. For example, since the powder has the property of adsorbing sebum components and the effect of deodorizing the body odor, the powder can be used for a sebum-adsorbent agent, a body deodorant and the like, therefore, the present invention contains these embodiments.
Now a sebum-adsorbent agent means an adsorbent agent for sebum, or an agent for adsorbing sebum.
Meanwhile, it suffices if the powder of the present invention comprises the aforementioned three components (that is the substance, the hydroxyapatite and the zinc oxide), and the powder of the present invention may compose other components or other structures, as far as the effect in the present invention is obtained or the object of the present invention is not obstructed. As a matter of course, these contents are contained in the powder of the present invention.
Meanwhile, as stated above, the sebum-adsorbent agent means a substance used for adsorbing, solidifying, or congealing the sebum of an animal, especially a human being. On the other hand, the body deodorant means a substance used for absorbing, solidifying, fixing, or deodorizing at least one of the components of disagreeable odor emitted through the skin of an animal, especially the skin of a human being, or from the epidermic cell (for example, due to perspiration (sweat) or effect of microorganisms and the like). In particular, the body deodorant may be used as the powder is mixed into the skin cosmetics or used as the powder mixed for deodorizing body odor separate from cosmetics.
In the present invention, the body odor (smell) components compose of a broad sense of body odor components which is emitted from the animal, especially the human body (see Seiichi Izaki, What is Body odor- its Cause and Prevention, Fragrance Journal, 1990-7, p.22 to 26 (1990); Yuuichi Yamamura, Body odor, xe2x80x98Modern Dermatology 2Bxe2x80x99 Whole Body and Skin 2, edited by Yuuichi Yamamura, Jun Kukita, Eishun Sano, Makoto Seiji, published by NAKAYAMA SHOTEN, Tokyo, 1981, 163).